1. Field of the Invention
The present invention relates to the field of removing residues from a substrate surface and, in particular, to removing residue material from electronic component substrates such as integrated circuits and semiconductor wafers.
2. Description of Related Art
Integrated circuits are formed from semiconductor substrates within and upon whose surfaces are formed resistors, transistors, diodes, wires, vias and other electrical circuit elements. The electrical circuit elements are connected internally and externally to the semiconductor substrate upon which they are formed through patterned conductor layers which are separated by dielectric layers. It is common in the art of integrated circuit fabrication to form vias and other apertures through the dielectric layers such that conductive connections may be made between the patterned conductor layers and the electrical circuit elements which are separated by the dielectric layers. Vias and other apertures within and/or through dielectric layers within integrated circuits may be formed through photolithographic methods followed by etch methods including but not limited to wet chemical etch methods, Reactive Ion Etch (RIE) and dry plasma etch methods.
The removal of various layers is usually accomplished through use of liquid or gaseous etchants. In cases where the reaction products are fluids, these are readily removed from the reaction site so that etching can proceed at a uniform rate. In certain cases, however, the reaction products are insoluble solids that are, at best, difficult to remove. Such etchants serve only to undermine, or weaken, the layer's integrity near the surface and, in the absence of any other action, are thus quite ineffective as etchants.
In many etching processes, mechanical assistance in the form of a slurry comprising an abrasive powder suspended in a suitable liquid medium (such as the etchant itself) can be used to complement the action of the chemical etchant. This technique for removing material through a combination of chemical and mechanical means is referred to as Chemical Mechanical Polishing (CMP). CMP also makes possible the controlled removal of material along a planar etch front, unlike pure fluid etches where the etch front tends to follow the contours of the original surface. CMP is therefore widely used for the planarization of integrated circuits. A disadvantage of CMP is that at the completion of a CMP operation some of the slurry tends to be left behind on the freshly polished surface.
The use of Super Critical Fluid (SCF) CO2 to clean or strip wafers is known. U.S. Pat. No. 5,976,264 is directed to stripping RIE residues from CF4 type etchants using SCF and a cryogenic aerosol wherein a relatively high pressure gas liquid mixture is allowed to rapidly expand into a region of lower pressure at cryogenic temperature, cooling the jet and causing the mixture to solidify. The use of Solid CO2 pellets is also known but not practical for large wafer bombardment.
Bearing in mind the problems and deficiencies of the prior art, it is therefore an object of the present invention to provide a method for removing solid and/or liquid residues from substrate surfaces including electronic components such as integrated circuits and semiconductor wafers.
A further object of the invention is to provide an apparatus for removing solid and/or liquid residues from electronic components such as integrated circuits and semiconductors.
Still other objects and advantages of the invention will in part be obvious and will in part be apparent from the specification.